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21.
The paper proposes a rational method to derive fairness measures for surfaces. It works in cases where isophotes, reflection lines, planar intersection curves, or other curves are used to judge the fairness of the surface. The surface fairness measure is derived by demanding that all the given curves should be fair with respect to an appropriate curve fairness measure. The method is applied to the field of ship hull design where the curves are plane intersections. The method is extended to the case where one considers, not the fairness of one curve, but the fairness of a one parameter family of curves. Six basic third order invariants by which the fairing measures can be expressed are defined. Furthermore, the geometry of a plane intersection curve is studied, and the variation of the total, the normal, and the geodesic curvature and the geodesic torsion is determined. 相似文献
22.
Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties)
polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They coincide with
the usual K-theoretic groups in the special case when the polytope is a unit simplex and can be thought of as compact/polytopal substitutes
for the tame automorphism groups of polynomial algebras. Relative to the classical case, many new aspects have to be taken
into account. We describe these groups explicitly when the underlying polytope is 2-dimensional. Already this low-dimensional
case provides interesting classes of groups.
Received: 13 December 2001 / Revised version: 24 June 2002
The second author was supported by the Deutsche Forschungsgemeinschaft, INTAS grant 99-00817 and TMR grant ERB FMRX CT-97-0107
Mathematics Subject Classification (2000): 14L27, 14M25, 19C09, 52B20 相似文献
23.
王巨平 《中国科学A辑(英文版)》2002,45(7):827-835
This paper verifies the singularity conjecture for Jacobi forms with higher degree in some typical cases, and gives constructions
for the Jacobi cusp forms whose Fourier coefficients can be expressed by some kind of Rankin-typeL-series. 相似文献
24.
Norbert Auner Larissa Zherlitsyna Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):m199-m200
The title compound, [Cu8(C8H24O2Si)2(C3H7NO)8]·C4H4N2·C3H7NO, features a sandwich‐like cage enclosing a pyrazine molecule, both situated on a centre of inversion. In addition, the crystal structure contains one dimethylformamide molecule which is disordered over a centre of inversion. The copper layer, containing eight atoms, is located between two siloxanolate fragments. The whole structure of Cu atoms and siloxanolate rings is distorted by the pyrazine molecule, leading to an oval form. As a result, the angles between the Cu atoms differ at the copper layer. The difference in the angles could lead to some deviations in the Cu–Cu exchange interactions within the copper ring, which is of interest for molecular magnetism. 相似文献
25.
It is explicitly shown that if phase transition occurs at the core of a newborn neutron star with moderately strong magnetic
field strength, which populates only the electron’s Landau levels, then in the β -equilibrium condition, the quark core is
energetically much more unstable than the neutron matter of identical physical condition. 相似文献
26.
Dimitar I. Pushkarov 《Central European Journal of Physics》2004,2(3):420-455
Basic ideas and results which characterize quantum diffusion of defects in quantum crystals like solid helium as a new phenomenon
are presented. Quantum effects in such media lead to a delocalization of point defects (vacancies, impurities etc.) and they
turn into quasiparticles of a new type—defectons, which are characterized not by their position in the crystal lattice but
by their quasimomentum and dispersion law. Defecton-defecton and defecton-phonon scattering are considered and an interpolation
formula for the diffusion coefficient valid in all interesting temperature and concentration regions is presented. A comparison
with the experimental data is made. Some alternative points of view are discussed in detail and the inconsistency of the Kisvarsanyi-Sullivan
theory is shown. 相似文献
27.
28.
In this paper we obtain a number of Maharam-type slice integral representations, with respect to scalar measures, for positive
projections in Dedekind complete vector lattices and f-algebras.
AMS Classification: 47B65, 46A40, 06F25 相似文献
29.
M. Lashkarizadeh Bami 《Semigroup Forum》2004,69(2):219-229
In the present paper it is shown that if S1 and S2 are two
Clifford topological semigroups satisfying certain conditions
and T is an isometric isomorphism of LUC(S1*) onto LUC(S2*), then T
maps S1 topologically isomorphically onto S2. Furthermore, T
maps M
l
n(S1) (M(S1), respectively) isometrically
isomorphically onto M
l
n(S2) (M(S2), respectively). Indeed,
we have obtained a generalization of a well-known result of
Ghahramani, Lau and Losert for locally compact groups to a more
general setting of Clifford topological semigroups. 相似文献
30.